Reflection type liquid crystal display apparatus and substrate for reflection type liquid crystal display

ABSTRACT

In order to provide a reflection type liquid crystal display apparatus where, even when the pixel size is small, the crosstalk between a signal line and an end of a capacitor can be decreased, thus resulting in a good output image, by forming a signal line  2  for transmitting an image signal to each pixel with a second metal layer, by placing a shield line  12  between a capacitor electrode  10  constituting a capacitor and the signal line  2  with a first metal layer, and by giving a fixed potential, shielding is provided to prevent occurrence of cross-talk. The capacitor is configured with a common electrode  11  and a capacitor electrode  10 , having a diffusion layer formed on a semiconductor substrate. By placing the capacitor electrode having a diffusion layer formed on the semiconductor substrate and the common electrode having a fixed potential below the signal line, shielding is provided to prevent occurrence of cross-talk.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reflection type liquid crystaldisplay apparatus using an active matrix type driving system, asubstrate for a reflection type liquid crystal, and a liquid crystalprojector system. More particularly, the present invention relates to areflection type liquid crystal display apparatus including asemiconductor substrate having a plurality of pixels disposed in amatrix thereon, each pixel including a switching element, a capacitorand an reflective electrode, and a light transmitting substrate having alight transmitting electrode formed thereon the reflective electrodefacing the light transmitting electrode, a substrate for a reflectiontype liquid crystal display apparatus using a semiconductor substrate,and a liquid crystal projector system.

2. Description of the Related Art

In recent years, liquid crystal display apparatuses are widely spreadfor applications from compact display apparatuses to terminals of socalled OA equipment (automated office equipment), in particular, in theoffice equipment, projection type liquid crystal display apparatuseswhere an image is projected on a large screen, are actively used.

With regard to such kinds of projection type liquid crystal displayapparatus, there are two main types: a transmission type liquid crystaldisplay apparatus and a reflection type liquid crystal displayapparatus. In the former transmission type liquid crystal displayapparatus, there is a problem in that, due to a switching element(transistor), a capacitor and a wiring provided to each of pixels, thetransmission region of a pixel for transmitting a light reduces apertureratio.

In the reflection type liquid crystal display apparatus, any regionexcept for a region for insulating and isolating an pixel electrode forreflection of each pixel (hereinafter referred to as a reflectiveelectrode) can be made as a reflective electrode. In addition, since aswitching element, a capacitor, and a wiring which are required fordriving an active matrix, can be arranged below the reflectiveelectrode, the reflection type liquid crystal display apparatus has manyadvantages as compared to the transmitting type liquid crystal displayapparatus, in compacting a liquid crystal display panel, highdefinition, and high brightness.

In general, in the above-mentioned reflection type liquid crystaldisplay apparatus, a plurality of reflective electrodes connected toswitching elements such as MOS transistors are arranged in a matrix on asemiconductor substrate (Si substrate). Moreover, the reflection typeliquid crystal display apparatus has a configuration where a lighttransmitting common electrode facing to the plurality of reflectiveelectrodes and to be common to all pixels, is placed, and further aliquid crystal is injected between the reflective electrodes of thesemiconductor substrate and the common electrode. In such a reflectiontype liquid crystal display apparatus, by incidenting a light from thecommon electrode side and by corresponding the potential differencebetween the common electrode and the reflective electrode to an imagesignal and by controlling the orientation of the liquid crystal in eachpixel, a reflected light is modulated.

In recent years, since high definition for the liquid crystal displayapparatus has been required, and the reflection type liquid crystaldisplay apparatus projects and displays an image on a large screen,needs of high definition pixels are big. Accordingly, if a highdefinition liquid crystal display apparatus is made by easygoing way ofthinking, the chip size of the semiconductor substrate tends to belarger and larger. However, the large chip size directly leads to costincrease. Therefore, it is desirable to make the chip size as small aspossible, and for this purpose, miniaturization of the pixel size isrequired.

In general, in consideration of reliability such as seizure, a voltageapplied to the liquid crystal of a liquid crystal display apparatus issubjected to so called inversion driving where the voltage applied tothe liquid crystal apparatus is reversed, for example, each frame.Therefore, a supply power voltage required to drive the liquid crystaldisplay apparatus is required to be an order of 15 V (or more). In otherwords, this means that the withstanding voltages of pixels formed on asemiconductor substrate and elements (transistors and capacitors)constituting a periphery drive circuit, are required to be an order of15 V (or more).

However, in order to ensure the withstanding voltage of each element,some amount of element size or element isolation space is required. Inother words, although a small pixel size is required, from the designrule of element formation (definition of sizes such as a pixel size andelement isolation space required when a device is formed), the sizecannot be caused to be small. Accordingly, in order to cause the elementsize to be small, the capacitor of each pixel tends to be small.

However, since, if the capacitor is caused to be small, the quantity ofan image is reduced and the image is susceptible to cross-talk from asignal line due to voltage drop caused by leakage from the capacitorend, the quantity of an output image will be reduced. Therefore, it isdesirable for the capacitor to be as large as possible.

In order to cause the capacitor of the pixel to be large, the size of acapacitor electrode in the pixel should be as large as possible.

FIG. 9 is an example of a conventional pixel layout, and FIG. 10 is across-sectional view along line 10-10 of FIG. 9. This configuration isdisclosed in Japanese Patent Application Laid-Open No. 2004-309681.

As a semiconductor substrate to be a base, a p-type mono-crystal siliconsubstrate (hereinafter, referred to as a p-type Si substrate) is used,and on the substrate a gate line 201 formed with polysilicon is wired ina horizontal direction. Then, a part of the gate wiring is separated andacts as a gate of NMOS transistor to be a switching element. A sourceregion 202 of a switching transistor to be a switching element isconnected to a signal line 204 formed with a first metal layer via asource contact 203. A drain region 205 of the switching transistor isconnected to a drain wiring 207 formed with the first metal layer via adrain contact 206. The drain wiring 207 is connected to a capacitorelectrode 209 formed with polysilicon via a contact 208.

The counter electrode of the capacitor electrode 209 acts as an N⁺ typediffusion layer formed on a silicon substrate by means of ionimplantation, and the diffusion layer acts as a common electrode 210being common to whole pixels. Moreover, an insulating film between thecapacitor electrode 209 and the common electrode 210 is generally formedby means of the same process as the process of a gate oxide film formingNMOS transistor.

In FIG. 10, a p-type Si substrate 211 is illustrated, where, in the leftside, an NMOS transistor acting as a switching element is formed betweenfield oxide films 212 a and 212 b. A gate electrode (a part of the gatewiring) 201 of the NMOS transistor, a source region 202, and a drainregion 205 are illustrated.

The source region 202 is connected to the signal line 204 formed withthe first metal layer via the source contact 203. The drain region 205is connected to the drain wiring 207 formed with the first metal layervia the drain contact 206. The drain wiring 207 is connected to thecapacitor electrode 209 via the contact 208, and further connected tothe reflective electrode 214 formed with a third metal layer via athrough hole 213. Moreover, since the common electrode (Vcom electrode)210 being the counter electrode of the capacitor electrode 209 is formedwith an N⁺ type diffusion layer, both sides thereof, similar to the NMOStransistor, are formed between the field oxide films 212 b and 212 c.Moreover, between the first metal layer and the reflective electrode214, in order to shielding incident light from the gap between itselfand a neighboring reflective electrode, a light shielding layer 215formed with the second metal layer is placed. In addition, in the lightshielding layer 215, at a position through which the through hole 213 ispassed, in order to obtain electrical insulation, a hole is opened. Inaddition, in order to obtain the capacitor of the pixel as much aspossible, a fixed potential is given to the shielding layer 215.

Although a liquid crystal layer 217 is not illustrated, it is insertedbetween liquid crystal common electrodes 216 at a predetermined gap,which are formed with a light transmitting substrate acting as a counterelectrode of the reflective electrode 214 after a protection film iscoated on the reflective electrode 214.

Since the change of the optical properties (change of polarizationcoefficient) of a liquid crystal occurs by the potential differencebetween the reflective electrode 214 and the liquid crystal commonelectrode 216, by controlling the potential of the reflective electrode214 of each pixel, an image is formed.

SUMMARY OF THE INVENTION

In Japanese Patent Application Laid-Open No. 2004-309681, a first shieldline 219 is provided between the signal line 204 and the drain wiring207, in the same layer (a first metal layer) as the layer of the signalline 204 and the drain wiring 207. Moreover, to the first shield line219 is given a potential being same as the potential of the commonelectrode 210. Furthermore, by also considering the effect of crosstalkfrom the signal line of a neighboring pixel, a second shield line 220 isalso arranged to a side (right side in the figure) opposite to the sidewhere the first shield line 219 is arranged. The second shield line 220gives a GND potential and connected to a p-type substrate via a P⁺region in the pixel. Although, in this configuration, crosstalkaffecting the drain wiring 207 by the signal line 204 includingneighboring pixels, can be suppressed, since the signal line 204 passesthrough a portion above the capacitor electrode 209, the cross-talk isnot eliminated. In other words, in order to cause the capacitor to belarger, a part of the capacitor electrode 209 is also made at the partbelow the signal line 204.

Here, what effect is given by cross-talk given by the signal line 204 tothe end of the capacitor electrode 209, will be described.

When a predetermined line is in a selection state (a state where a gateline is in a high level and the switching transistor of the pixel is inan on state), each pixel in another line holds a pixel signal voltagefor displaying the pixel in the capacitor thereof. At that time, imagesignal is written into the held capacitor on the predetermined pixel bythe signal line via the switching transistor. At that time, asillustrated in FIG. 9, since a parastic capacitor is present between thesignal line 204 and the end of the capacitor 209, potential fluctuationoccurs at the end of the electrode of a capacitor in a held state, viathe parastic capacitor. If the potential of the electrode of thecapacitor in a held state is changed, optical properties of a liquidcrystal is changed, and thereby, an original image cannot be expressed,thus resulting in significant degradation of image quality. Thisphenomenon is referred to as a cross-talk.

Evaluation pattern for measuring the cross-talk is performed using, forexample, a nine-split screen (three-split in horizontaldirection×three-split in vertical direction). When 100% of brightness isdisplayed on the center split screen, and a half tone brightness (forexample, 10% of brightness) is displayed on the surrounding eight splitscreens, the cross-talk due to the parastic capacity occurs at theinterface of the brightnesses.

In order to avoid the cross-talk, it can be considered that aconfiguration where the capacitor electrode 209 formed with polysilicon,that is a capacitor, is not placed below the signal line 204 in otherwords, a capacitor is not formed. Using this layout, overlapping betweenthe signal line 204 and capacitor electrode 209 is not present, thereby,the cross-talk given to the end of the capacitor electrode by the signalline 204 can be caused to be small, however, the capacitor becomessmall. In this situation, when the size of the pixel is small, theretention capability of a pixel voltage degrades. When the retentioncapability is degraded, the image becomes an image whose contrast issmall, thus resulting in degradation of the quality of the image.

In addition, between the signal line 204 and the reflective electrode214, a light shielding layer 215 for shielding incident light from thegap between reflective electrodes, is placed. Since a fixed voltage isapplied to the light shielding layer 215, and the light shielding layer215 acts as a shield layer, a configuration where the cross-talk givento the reflective electrode 214 by the signal line 204 hardly occurs, isobtained.

As mentioned above, usually, it is known that the cross-talk is notrecognized by human eyes when the relative difference of brightness ofthe neighboring pixels is equal to or smaller than 2 to 3%.

In recent years, high definition of a display apparatus has beenadvanced, and, accordingly, if the pixel size is not also caused to besmall, the cost cannot be suppressed. However, as mentioned above, fromthe view point of reliability, the drive of the liquid crystal isgenerally a inversion driving. The power supply voltage required for thereverse drive is an order of 10 to 15 V, and the transistor and thecapacitor formed on the Si substrate are required to have withstandingvoltages for stably operating with respect to the power supply voltage.Therefore, even if the pixel size is small, the size where the elementsare formed (for example, width of element isolation or the like) cannotbe readily made small. Further, in order to obtain a pixel structurethat has resistance to the cross-talk, it is desirable for the capacitorto be as large as possible.

The object of the present invention is to decrease cross-talk given toan end of a capacitor (a drain wiring, a capacitor electrode, and areflective electrode) by a signal line by forming a switching elementand a large capacitor in a limited pixel size, and, as the results, toprovide a reflection type liquid crystal display apparatus which canobtain a high quality image.

The reflection type liquid crystal display apparatus of the presentinvention includes: a light transmitting substrate having a lighttransmitting electrode; a liquid crystal layer; and a substrateincluding a pixel which has a switching element, a capacitor and areflective electrode, and a signal line which is connected to thecapacitor and the reflective electrode via the switching element andplaced on a portion above at least a part of the capacitor; and arrangedso that the light transmitting electrode faces to the reflectiveelectrode sandwiching the liquid crystal layer therebetween; where,between the capacitor and the signal line, a layer to which a fixedpotential is supplied, is arranged.

Moreover, the reflection type liquid crystal display apparatus of thepresent invention includes: a light transmitting substrate having alight transmitting electrode; a liquid crystal layer; and semiconductorsubstrate including a pixel which has a switching element, a capacitorand a reflective electrode, a signal line which is connected to thecapacitor and the reflective electrode via the switching element andplaced on a portion above at least a part of the capacitor; and arrangedso that the light transmitting electrode faces to the reflectiveelectrode sandwiching the liquid crystal layer therebetween; where thecapacitor includes a first electrode having a diffusion layer formed inthe semiconductor substrate, and a second electrode having a secondconductive layer arranged between the signal line and the firstelectrode, and the first electrode is connected to the switchingelement, and a fixed potential is supplied to the second electrode.

A substrate for the reflection type liquid crystal display apparatus ofthe present invention includes: a pixel having a switching element, acapacitor, and a reflective electrode; a signal line which is connectedto the capacitor and the reflective electrode via the switching elementand placed on a portion above at least a part of the capacitor; and alayer placed between the capacitor and the signal line, to which a fixedpotential is supplied.

Moreover, the substrate for the reflection type liquid crystal displayapparatus of the present invention includes: a semiconductor substrateincluding a pixel having a switching element, a capacitor, and areflective electrode; and a signal line which is connected to thecapacitor and the reflective electrode via the switching element andplaced on a portion above at least a part of the capacitor; where thecapacitor includes a first electrode having a diffusion layer formed onthe semiconductor substrate, and a second electrode having a secondconductive layer arranged between the signal line and the firstelectrode, and the first electrode is connected to the switchingelement, and a fixed potential is supplied to the second electrode.

According to the present invention, even if the pixel size is small, alarge capacitance value of the capacitor can be obtained, thereby,cross-talk from the signal line to the drain wiring of the switchingtransistor, the capacitor electrode, and the reflective electrode, canbe decreased. As the results, it is possible to provide a reflectiontype liquid crystal display apparatus which can obtain a good outputimage.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a pixel illustrating a firstembodiment of the present invention.

FIG. 2 is a cross-sectional view along line 2-2 in FIG. 1.

FIG. 3 is a cross-sectional view along line 3-3 in FIG. 1.

FIG. 4 is a schematic plan view of a pixel illustrating a secondembodiment of the present invention.

FIG. 5 is a cross-sectional view along line 5-5 in FIG. 4.

FIG. 6 is a cross-sectional view along line 6-6 in FIG. 4.

FIG. 7 is a block diagram describing an active matrix drive circuit in areflection type liquid crystal display apparatus of the presentinvention.

FIG. 8 is a view illustrating a liquid crystal projector system.

FIG. 9 is a schematic plan view of a prior art pixel.

FIG. 10 is a cross-sectional view along line 10-10 in FIG. 9.

FIG. 11 is a layout view of a matrix of an example, where pixels in FIG.1 are arranged in 4×4.

FIG. 12 is a layout view of a matrix of another example, where pixels inFIG. 1 are arranged in 4×4.

FIG. 13 is a layout view of a matrix of another example, where pixels inFIG. 1 are arranged in 4×4.

FIG. 14 is a layout view of a matrix of another example, where pixels inFIG. 1 are arranged in 4×4.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will de described indetail by using drawings.

Embodiment 1

FIG. 1 is a schematic plan view of a pixel illustrating a firstembodiment of the present invention, FIG. 2 is a cross-sectional viewalong line 2-2 in FIG. 1, and FIG. 3 is a cross-sectional view alongline 3-3 in FIG. 1. FIG. 7 is a block diagram describing a drive circuitof an active matrix in a reflection type liquid crystal displayapparatus of the present invention. In addition, in FIG. 1, for ease ofseeing the drawing, only the side (a reflective electrode, a lightshielding layer, and a through hole connected to the reflectiveelectrode are not included) of a Si substrate (semiconductor substrate)from a light shielding layer illustrated in FIG. 2 is described. Inaddition, in this embodiment, a p-type Si substrate is used as asemiconductor substrate having an active matrix drive circuit, and aswitching element is assumed to be a switching transistor having an NMOStransistor. Moreover, a circuit operation as a liquid crystal displayapparatus, will be described with reference to FIG. 7.

FIG. 7 is a block diagram describing an active matrix drive circuit in areflection type liquid crystal display apparatus of the presentinvention, and in FIG. 7, for simplicity of description, 3×3 pixels arearranged, and circuitry of each pixel is also described.

The active matrix drive circuit illustrated in FIG. 7, is assumed to beformed on a p-type Si substrate.

In FIG. 7, a pixel 101 is illustrated. The pixel 101 is configured witha switching element 102 having a switching transistor or the like, acapacitor 103, and a reflective electrode 104. The switching element 102in the pixel is configured with an NMOS transistor. Gates of switchingelements 102 in a pixel of the same line are connected to a gate line105, to which an output of each resistor of vertical scanning shiftregisters 106 is applied. Sources (the left side of an illustratedtransistor) of switching elements 102 in a same column are connected toa signal line 107. A drain of the switching element 102 of each pixel isconnected to one end of the capacitor 103 and the reflective electrode104, and the other end of the capacitor 103 is connected to a Vcompotential being common to all pixels. The signal line 107 is connectedto a video line via a transferring switch 108. On/off of thetransferring switch 108 is controlled by each register output ofhorizontal scanning shift registers 110.

The operation of an active matrix drive circuit illustrated in FIG. 7,will be described briefly. Video signals sequentially input at shiftedtiming are output to the video line 109. Then, by sequentially turningthe transferring switches 108 to be in an on-state (conduction state)using the vertical scanning shift register 110, video signal voltagesare sampled and supplied to the signal line 107. The switching elementof a desired pixel locating at a position where the single signal line107 and the gate line 105 selected by the vertical scanning shiftregister 106 intersect each other, is selected and turned to be inon-state. Then, the video signal voltages are written in the capacitor103 of the pixel via the switching element 102. The voltage of thereflective electrode 104 is the voltage written in the capacitor 103.Then, the potential difference created between the reflective electrode104 and a light transmitting common electrode (not illustrated in thefigure) is applied to a liquid crystal, thus resulting in change ofoptical properties of the liquid crystal.

In FIGS. 1 and 2, a gate line 1 formed with polysilicon (correspondingto a second electrode) is illustrated, and a part of the gate line 1 isbranched and acts as the gate of a switching transistor. A signal line 2formed with a second metal layer (corresponding to a first conductivelayer) is connected to source regions 3 of the switching transistors ofpixels arranged in a column direction through the source contact 4. Thesignal line 2 formed with the second metal layer is connected to asource wiring 5 via a through hole, which is formed with a first metallayer (corresponding to a third conductive layer) below the second metallayer, and subsequently connects the source wiring 5 and the sourceregion 3 via the source contact 4. The drain region 7 of the switchingtransistor is connected to a drain wiring 8 formed with the first metallayer, via a drain contact 6. The first drain wiring 8 is connected to asecond drain wiring 9 (wiring pattern) formed with the second metallayer, via the through hole. Further, similar to the prior art, thesecond drain wiring 9 passes through the hole in a light shielding layer17 and is connected to a reflective electrode 16 via the trough hole.Although being not illustrated in the figure, a liquid crystal layer 19is sandwiched between liquid crystal common electrodes 18 at apredetermined gap, which act as light transmitting electrodes formedwith a light transmitting substrate acting as the counter electrode ofthe reflective electrode 16, after a protective film is formed on thereflective electrode 16. Where, with regard to the first and secondlayers, metallic material such as Al is suitably used, however, they arenot limited to it, an conductive layer may be used, where electricalconduction is possible.

Moreover, the first drain wiring 8 is connected to a capacitor electrode10 formed with polysilicon (corresponding to the second conductivelayer) below the first contact, via the first contact. The capacitorelectrode 10 together with a common electrode 11 (Vcom electrode) formedwith an N⁺ type diffusion region, by sandwiching an oxide filmcomparable to a gate oxide film forming a switching transistor, formsthe capacitor of each pixel.

At a portion above the gate electrode of the switching transistor, afirst shield line 12 (acts as a shield layer) is provided between thesource wiring 5 formed with the first metal layer (corresponding to thethird conductive layer) and connected to the signal line 2, and thedrain wiring 8 formed with the first metal layer (corresponding to thethird conductive layer).

By applying a predetermined constant voltage to the first shield line 12so as to be a fixed potential, the first shield line 12 acts as a shieldso that cross-talk from the source wiring 5 to the first drain wiring 8does not occur.

Further, at a portion above the first shield line 12, a second shieldline 13 formed with the second metal layer (corresponding to the firstconductive layer) is present. In addition, the shield line 13 is placedbetween the signal line 2 and the second drain wiring 9 formed with thesignal line 2 and the second metal layer (corresponding to the firstconductive layer). Similar to the first shield line 12, by being appliedby a predetermined constant voltage so as to be a fixed potential, thesecond shield line 13 shields so that cross-talk from the signal line 2to the second drain wiring 9 does not occur. Moreover, the first shieldline 12 is connected to the common electrode 11 (N⁺ diffusion layer)constituting a capacitor, via the second contact.

Further, as illustrated in FIG. 3, the portion above the capacitor iswidely patterned so that the first shield line 12 is placed between thecapacitor 10 formed with polysilicon (corresponding to the secondconductive layer) and the signal line 2 formed with the second metallayer (corresponding to the first conductive layer).

By this, a portion between the signal line 2 and the capacitor electrode10 is shielded, thereby, cross-talk from the signal line hardly affectsthe capacitor electrode 10.

Moreover, in the right-hand side (right-hand side of a pixel) in FIG. 1,a shield line 14 formed with the first metal layer (corresponding to thethird conductive layer) is placed, and, at a position where thecapacitor is not formed, connected to the P⁺ region via a third contactso as to be the potential of a p type Si substrate. Further, asillustrated in FIGS. 1 and 3, at a portion above the shield line 14, ashield line 15 formed with the second metal layer (corresponding to thefirst conductive layer) is placed. By this, the shield line 14 acts as ashield to the source wirings 5 of neighboring pixels, and the shieldline 15 acts as a shield to the signal lines of neighboring pixels. InFIG. 11, a plurality of pixels illustrated in FIG. 1 is arranged in a4×4 matrix. In this embodiment, all pixels are arranged in substantiallysame direction. As illustrated in FIG. 11, between the signal line 2 andthe drain line 9 of a predetermined pixel, the shield line 13 of thepixel is placed. Moreover, between the signal line 2 and the drainwiring 9 of a neighboring pixel of the predetermined pixel, the shieldline 15 of the neighboring pixel is placed. Further, between the sourcewiring 5 and the drain wiring 8 of a predetermined pixel, the shieldline 12 is placed, and between the source wiring 5 and the drain wiring8 of a neighboring pixel of the predetermined pixel, the shield line 14is placed. By such a configuration, it is possible to decrease theoccurrence of cross-talk. Moreover, since regions from the reflectiveelectrode 16 where a liquid crystal layer is sealed, to the liquidcrystal common electrode has the same structure as the structure ofprior art, description thereof will be omitted.

In addition, in this embodiment, the matrix layout of pixels is notlimited to the layout illustrated in FIG. 11, for example, matricesillustrated in FIGS. 12 to 14, are also suitably applicable.

In FIG. 12, a plurality of pixels illustrated in FIG. 1 is arranged in a4×4 matrix. In FIG. 12, pixels in odd columns and pixels in even columnsare arranged so that they are in line symmetry in horizontal direction(lateral direction in the figure). When this configuration is used, itis required for pixel voltages to be written every 2N pixels (where N isa positive integer) simultaneously. In the configuration illustrated inFIG. 12, between the signal line 2 and the drain wiring 9, the shieldline 13 or the shield line 15 is also placed. Moreover, between thesource wiring 5 and the drain wiring 8, the shield line 12 or the shieldline 14 is also placed. By these configurations, occurrence of thecross-talk can be decreased.

In FIG. 13, a plurality of pixels illustrated in FIG. 1 is also arrangedin a 4×4 matrix. In FIG. 13, pixels in odd columns and pixels in evencolumns are arranged so that they are in line symmetry in verticaldirection (longitudinal direction in the figure). In the configurationillustrated in FIG. 13, between the signal line 2 and the drain wiring9, the shield line 13 or the shield line 15 is also placed. Moreover,between the source wiring 5 and the drain wiring 8, the shield line 12or the shield line 14 is also placed. By these configurations,occurrence of the cross-talk can be decreased.

In FIG. 14, a plurality of pixels illustrated in FIG. 1 is also arrangedin a 4×4 matrix. In FIG. 14, pixels in odd columns and pixels in evencolumns are arranged so that they are in line-symmetry in horizontaldirection (lateral direction in the figure) and in line-symmetry invertical direction (longitudinal direction in the figure). When thisconfiguration is used, similar to the configuration illustrated in FIG.12, it is required for pixel voltages to be written every 2N pixels(where N is a positive integer) simultaneously. In the configurationillustrated in FIG. 14, between the signal line 2 and the drain wiring9, the shield line 13 or the shield line 15 is also placed. Moreover,between the source wiring 5 and the drain wiring 8, the shield line 12or the shield line 14 is also placed. By these configurations,occurrence of the cross-talk can be decreased.

Here, the matrix layout of pixels is not limited to the layoutillustrated in this embodiment, it is also suitably applicable to otherembodiments of the present invention.

In addition, in regions among respective layers (such as electrode andwiring) illustrated in FIGS. 2 and 3 not described in particular,insulating layers are placed.

Further, although the reflective electrode 16 also forms one end of thecapacitor, the light shielding layer 17 is placed between the signalline 2 and the reflective electrode 16. Since, a predetermined constantvoltage is applied to the light shielding layer 17 to be a fixedpotential, the light shielding layer 17 acts as a shield layer, thus,resulting in suppression of effect of cross-talk from the signal line 2to the reflective electrode 16. Moreover, by applying the constantvoltage to the light shielding layer 17, the portion between thereflective electrode 16 and the light shielding layer 17 can be alsoused as the capacitor.

As mentioned above, by using the pixel layout illustrated in thisembodiment, a wiring pattern with predetermined constant voltages in thevertical and horizontal directions of the signal line, is arranged. Bythis configuration, since the signal line is shielded in four directions(in vertical directions and in horizontal directions), and the portionbelow the signal line can be also effectively formed as the capacitor,the capacitance value can be large. Further, since cross-talk given tothe drain wiring, the capacitor electrode and the reflective electrodecan be decreased, even when the pixel size is small, a good output imagecan be obtained.

Moreover, in this embodiment, an example using a p type Si substrate isdescribed, however, an n type Si substrate may also be used, and evenwhen either substrate is used, effects according to this embodiment doesnot change.

Furthermore, in this embodiment, as the gate line, polysilicon is used;however, the gate line is not necessarily to be polysilicon. Thus, aconfiguration may be used, where the gate line is formed by using thefirst metal layer, and, at a required position, connected to polysiliconvia a contact, and the polysilicon constitutes the gate of a switchingtransistor.

Embodiment 2

FIG. 4 is a schematic plan view illustrating a second embodiment of thepresent invention, and FIG. 5 is a cross-sectional view in along line5-5 in FIG. 4. Moreover, FIG. 6 is a cross-sectional view in along line6-6 in FIG. 4.

The main difference between this embodiment and the first embodiment isin that an electrode having an N⁺ type diffusion layer, which is thefirst electrode of the capacitor, is brought into contact to the drainregion of a switching transistor, and connected to the drain wiring andthe reflective electrode, and, in that the common electrode, which isthe second electrode forming the capacitor, is formed with polysiliconand connected to a shield line. In this embodiment, a layercorresponding to the second metal layer in Embodiment 1 is notnecessary.

Hereinafter, the pixel layout and the cross-sectional structureillustrated in FIG. 4 will be described.

A part of a gate line 1 formed with polysilicon is branched and acts thegate of a pixel switching transistor. A signal line 2 a formed with thefirst metal layer is connected to the source regions 3 of switchingtransistors of pixels arranged in a column direction via a sourcecontact 4. The drain region 7 of the switching transistor is connectedto the drain wiring 8 formed with the first metal layer via a draincontact 6, and the drain wiring 8 is connected to the reflectiveelectrode 16 via a through hole.

Moreover, without requiring element isolation between a transistor and acapacitor, the drain region 7 is connected to a capacitor electrode 10 aformed with an N⁺ diffusion layer, in the extension of the diffusionregion. The capacitor electrode 10 a together with a common electrode 11a (Vcom electrode) formed with polysilicon, by sandwiching an oxide filmcomparable to a gate oxide film forming a switching transistor, formsthe capacitor of each pixel.

At a portion above the gate electrode (a part of the gate wiring) of theswitching transistor, the shield line 12 formed with the first metallayer is present, and the shield line 12 is placed between the signalline 2 a and the drain wiring 8 formed with the first metal layer. Bybeing applied with a predetermined constant voltage, the shield line 12shields so that cross-talk from the signal line 2 to the drain wiring 8does not occur. The shield line 12 is connected to the common electrode11 a constituting a capacitor, via a contact.

Further, the common electrode 11 a formed with polysilicon is placedbetween the signal line 2 formed with the first metal layer and thecapacitor electrode formed with an N⁺ diffusion region. Therefore, theportion between the signal line 2 and the capacitor electrode 10 a isshielded, and, thereby, there is no influence of not affected by thecross-talk from the signal line.

Moreover, in the right-hand side (right-hand side of a pixel) in FIG. 4,a GND shield line 14 formed with the first metal layer is placed, and,at a position where the capacitor is not formed, connected to the P⁺region via a contact so as to be the potential of a p-type Si substrate.By this, the GND shield line 14 acts as a shield to the signal lines ofneighboring pixels. Moreover, since the light shielding layer 17,similar to the case in Embodiment 1, is placed with a desired constantpotential, there is no cross-talk affected by the signal line 2 to thereflective electrode 16. Moreover, since regions from the reflectiveelectrode 16 where a liquid crystal layer 19 is sealed, to the liquidcrystal common electrode 18 has the same structure as in Embodiment 1,description thereof will be omitted.

In addition, in regions among respective layers (such as electrode andwiring) illustrated in FIGS. 5 and 6 not described in particular,insulating layers are placed.

As mentioned above, by using the pixel layout illustrated in thisembodiment, a wiring pattern with predetermined constant voltages in thevertical and horizontal directions of the signal line, is arranged. Asthe results, since the signal line is shielded from four directions (invertical directions and in horizontal directions), and the portion belowthe signal line can be also effectively formed as the capacitor, thecapacitance value can be large. Further, since cross-talk given to thedrain wiring, the capacitor electrode and the reflective electrode canbe decreased, even when the pixel size is small, a good output image canbe obtained.

Moreover, in this embodiment, an example using a p type Si substrate isdescribed, however, an n type Si substrate may also be used, and evenwhen either substrate is used, effects demonstrated by the presentembodiment does not change.

In addition, in the configuration of the present embodiment, the presentinvention can be achieved even if the number of metal layers is less byone than the number of the configuration of the first embodiment.

Embodiment 3

Now, with reference to FIG. 8, a liquid crystal projector system using areflection type liquid crystal display apparatus which uses an activematrix substrate of the present invention, will be described. In FIG. 8,an example of an optical system for a liquid crystal projector isillustrated. A lump 1101, a reflector 1102, a rod integrator 1103, acollimater lens 1104, a polarization converting system 1105, a relaylens 1106, and a dichroic mirror 1107 are illustrated. Moreover, apolarization beam splitter 1108, a cross-prism 1109, a reflection typeliquid crystal panel using an active matrix substrate of the presentinvention 1110, a projection lens 1111, and a total reflection mirror1112 are illustrated.

Light flux emitted from the lamp 1101 is reflected by the reflector1102, and focused in the entrance of the integrator 1103. The reflector1103 is an elliptic reflector and its focal points are present in alight emitting part and the entrance of the integrator. The light fluxentered the integrator 1103 is reflected for 0 to several times in theintegrator, and forms a secondary light source image in the exit of theintegrator. Although, as a method for forming the secondary lightsource, there is a method using a fly eye, here it is eliminated. Thelight flux from the secondary light source is caused to be substantiallyparallel lights through the collimater lens 1104 and enters thepolarization beam splitter 1105 of the polarization converting system. Pwaves are reflected by the polarization beam splitter 1105, passedthrough a λ/2 plate to become an S wave, and all of them become S wavesand enter the relay lens 1106. The light flux is condensed in a panel bythe relay lens 1106. While condensing the light flux in the panel, acolor decomposition system is constituted by a color decompositiondichroic mirror 1107, a polarizing plate (not illustrated in thefigure), the polarization beam splitter 108, and the cross-prism 1109etc., and S waves enter three liquid crystal panels 1110. In the liquidcrystal panel 1110, a liquid crystal shutter controls the voltage ineach pixel while synchronizing to the picture image. A mode where an Swave is modulated into an elliptically polarized light (or a linearlypolarized light) by the operation of the liquid crystal, the P wavecomponent is transmitted by the polarization beam splitter 1108, a colorthereof is synthesized by the cross prism 1109, and, subsequently, isprojected from the projection lens 1111, is general.

The present invention can be applied to a reflection type liquid crystaldisplay apparatus, a substrate for the reflection type liquid crystaldisplay apparatus, and a liquid crystal projector system displaying animage and a character using a liquid crystal.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application Nos.2006-123411, filed Apr. 27, 2006, and 2007-106059 filed Apr. 13, 2007which are hereby incorporated by reference herein in their entirety.

1-16. (canceled)
 17. A reflection type liquid crystal display apparatuscomprising: a light transmitting substrate having a light transmittingelectrode; a liquid crystal layer; and a semiconductor substrate havingpixels, each of which has a switching element, a capacitor and areflective electrode, and having a signal line connected to thecapacitor and the reflective electrode via the switching element andplaced above at least a part of the capacitor, and arranged so that thelight transmitting electrode faces to the reflective electrodesandwiching the liquid crystal layer therebetween; wherein the capacitorincludes a first electrode connected to the switching element and asecond electrode, to which a fixed potential is supplied, opposite tothe first electrode and arranged between the signal line and the firstelectrode.
 18. The reflection type liquid crystal display apparatusaccording to claim 17, wherein the switching element and the reflectiveelectrode are connected via a wiring pattern; the wiring patterncomprises the same material as the material of the signal line; and ashield wiring, to which a fixed potential is supplied, is placed betweenthe signal line and the wiring pattern in lateral.
 19. The reflectiontype liquid crystal display apparatus according to claim 18, wherein theplurality of pixels is arranged in a matrix, and, between a wiringpattern of a neighboring pixel and the signal line, a shield wiring ofthe neighboring pixel to which a fixed potential is applied is arranged.20. The reflection type liquid crystal display apparatus according toclaim 17, wherein, between the reflective electrode and the signal line,a light shielding layer to which a fixed potential is supplied, isplaced.
 21. The reflection type liquid crystal display apparatusaccording claim 18, wherein the second electrode and the shield wiringare connected via a through hole.
 22. A liquid crystal projector systemcomprising the reflection type liquid crystal display apparatusaccording to claim
 17. 23. A substrate for a reflection type liquidcrystal display apparatus used in a reflection type liquid crystaldisplay apparatus, comprising: a semiconductor substrate having pixels,each of which has a switching element, a capacitor, and a reflectiveelectrode, and having a signal line connected to the capacitor and thereflective electrode via the switching element and placed on a portionabove at least a part of the capacitor; wherein the capacitor includes afirst electrode formed connected to the switching element and a secondelectrode, to which a fixed potential is supplied, opposite to the firstelectrode and arranged between the signal line and the first electrode.